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 * Copyright (c) 1997, 2007, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package com.sun.jmx.snmp.IPAcl;


import java.util.Vector;
import java.io.Serializable;

import java.security.Principal;
import java.security.acl.Owner;
import java.security.acl.LastOwnerException;
import java.security.acl.NotOwnerException;


/**
 * Owner of Access Control Lists (ACLs).
 * The initial owner Principal should be specified as an
 * argument to the constructor of the class AclImpl.
 *
 * @see java.security.acl.Owner
 */

class OwnerImpl implements Owner, Serializable {

  private static final long serialVersionUID = -576066072046319874L;

  private Vector<Principal> ownerList = null;

  /**
   * Constructs an empty list of owner.
   */
  public OwnerImpl() {
    ownerList = new Vector<Principal>();
  }

  /**
   * Constructs a list of owner with the specified principal as first element.
   *
   * @param owner the principal added to the owner list.
   */
  public OwnerImpl(PrincipalImpl owner) {
    ownerList = new Vector<Principal>();
    ownerList.addElement(owner);
  }

  /**
   * Adds an owner. Only owners can modify ACL contents. The caller principal
   * must be an owner of the ACL in order to invoke this method. That is, only
   * an owner can add another owner. The initial owner is configured at
   * ACL construction time.
   *
   * @param caller the principal invoking this method. It must be an owner of the ACL.
   * @param owner the owner that should be added to the list of owners.
   * @return true if successful, false if owner is already an owner.
   * @throws NotOwnerException if the caller principal is not an owner of the ACL.
   */
  public boolean addOwner(Principal caller, Principal owner)
      throws NotOwnerException {
    if (!ownerList.contains(caller)) {
      throw new NotOwnerException();
    }

    if (ownerList.contains(owner)) {
      return false;
    } else {
      ownerList.addElement(owner);
      return true;
    }
  }

  /**
   * Deletes an owner. If this is the last owner in the ACL, an exception is raised.
   * <P>
   * The caller principal must be an owner of the ACL in order to invoke this method.
   *
   * @param caller the principal invoking this method. It must be an owner of the ACL.
   * @param owner the owner to be removed from the list of owners.
   * @return true if successful, false if owner is already an owner.
   * @throws NotOwnerException if the caller principal is not an owner of the ACL.
   * @throws LastOwnerException if there is only one owner left, so that deleteOwner would leave the
   * ACL owner-less.
   */
  public boolean deleteOwner(Principal caller, Principal owner)
      throws NotOwnerException, LastOwnerException {

    if (!ownerList.contains(caller)) {
      throw new NotOwnerException();
    }

    if (!ownerList.contains(owner)) {
      return false;
    } else {
      if (ownerList.size() == 1) {
        throw new LastOwnerException();
      }

      ownerList.removeElement(owner);
      return true;
    }
  }

  /**
   * Returns true if the given principal is an owner of the ACL.
   *
   * @param owner the principal to be checked to determine whether or not it is an owner.
   * @return true if the given principal is an owner of the ACL.
   */
  public boolean isOwner(Principal owner) {
    return ownerList.contains(owner);
  }
}
